Various parameters are monitored in gas and steam turbine installations in order to enable optimum operation. In this context, reference can be made, for example, to sensor system arrangements which are used to detect noise in combustion chambers of gas turbines or vibrations in or on turbine parts in order to control operating parameters such that a low-vibration or optimum operating sequence is ensured.
In this case, there is regularly the need to monitor the sensor system for error-free operation and/or to use the sensor signals to derive correlated variables which are needed for the operation of the control system.
Therefore, the central processor arrangement must carry out extensive preliminary work before generating output commands for operation control elements or elements for controlling the supply of fuel or air to a combustion process. This is synonymous with various processor functions having to be adapted to the sensor system used in each case.
This results in the problem of a subsequent design modification of the sensor system not being readily possible, for example because the design modification results in a modified signal format of the sensor system and this modified signal format cannot be readily processed.
WO 2004/005938 A1 discloses an apparatus for determining the rotational speed of a rotating machine part with redundant sensors and evaluation circuits. The apparatus disclosed there is constructed from two partial apparatuses which are arranged in a parallel manner and are each in the form of separate channels. One of the partial apparatuses suffices to perform the task of monitoring the rotational speed. A sensor signal is evaluated by two evaluation circuits in each case. “Two out of three” redundancy is provided with respect to the rotational speed signals in each partial apparatus, that is to say one of the at least three rotational speed signals applied to the signal inputs of each partial apparatus may be erroneous without the monitoring function of each partial apparatus being jeopardized thereby. Although a high degree of availability and reliability of the installation is achieved with this technical solution, an increased outlay on apparatus must be disadvantageously accepted.